The present invention relates to a method of and a machine for planting seeds in general and more particularly to a machine of this type which is also capable of breaking up the soil prior to the actual planting operation.
There are already known various machines of the type here under consideration which are capable of both breaking up the soil and planting seeds therein. Such conventional machines are either towed behind a tractor or self-propelled to move over the field to be tilled, include at their front portion either stationary tools, such as plowing blades or cultivator tines, or movable tools such as disks rotating about a horizontal axis or prongs or similar tools orbiting around vertical axes. Immediately behind these breaking-up tools, there are provided arrangements which cause the seeds to be planted to become deposited on, or penetrate into the ground. Such arrangements, which usually are constructed as tubes, more often than not, discharge the seeds at a zone where the soil broken up by the breaking-up tool descends onto the ground. It is also known to equip the conventional machines of this type with a compacting roller which serves the dual purpose of compacting the upper layer of the soil at the region of deposition of the seeds, and of controlling the working depth of the breaking-up tools.
Experience with these conventional machines has shown that they are disadvantageous in several respects. One of the serious drawbacks of these conventional machines is that the seeds are not deposited in or on the ground under conditions which would be most conducive to their subsequent growth. As a matter of fact, the depth below the surface at which the seeds planted by the conventional machine are located varies within relatively wide limits. This is due partly to the fact that the seeds already deposited on or travelling toward the ground are entrained by the soil travelling rearwardly from the breaking-up tools for joint travel therewith in the rearward direction, and partly to the fact that the seeds become deposited on soil which has been previously broken up or loosened but which has not been tamped or compacted prior to the deposition of the seeds thereon. As a result of the latter situation, the seeds can fall into cracks or other gaps in the ground, such as gaps present between adjacent soil granules or aggregates. It is well known that a seed which is situated more than 10-15 cms. below the upper surface of the ground after the planting does not germinate. In addition thereto, if the upper layer of the soil is too loose, moisture from the subsoil is hindered in rising toward the seeds due to capillary action so that the seeds may be deprived of the moisture needed for their growth. On the other hand, if the upper layer of the soil is too loose, the latter dries out very rapidly after being moistened by rain or other precipitation, which also impedes the growth of the plants from the seeds.